The present invention relates to equipment for modifying the surface of an existing road, and in particular to equipment for smoothing areas of existing pavement by removing bumps and other upward projections.
A variety of apparatus is known in the prior art designed to remove bumps and other irregularities on the surface of a road, runway, taxiway, or other stretch of pavement. For example, Gillespie, U.S. Pat. No. 1,630,422, discloses a road planning device having a rotary cutting element powered by an engine mounted in a generally rectangular frame designed to be towed behind a tractor. Four supports for the frame contact the underlying pavement and are longitudinally adjustable to accommodate differences in the initial smoothness of the pavement. Hatcher, U.S. Pat. No. 4,256,344, discloses a concrete surfacing machine having a carriage with front and rear wheels at its ends which support the carriage for movement along a surface to be worked. Mounted on this carriage between the wheels is a concrete surface smoothing or planing machine having a motor driven rotary cylindrical cutting drum. The carriage has a propulsion unit for propelling the carriage along the surface that includes a drive system for the carriage wheels for use on relatively level surfaces and a winch drive for use on slopes. Both the vertical and horizontal position of the wheels are adjustable relative to the cutting drum
Staab et al. U.S. Pat. No. 4,516,808, discloses a pavement grinding apparatus that includes a main frame having a plurality of wheels supporting the main frame on the paved surface. Means are provided for propelling the main frame across the paved surface in a desired direction. A sub-frame is disposed within the main frame. At least one movable connector attaches the main frame to the sub-frame for imparting substantially horizontal, longitudinal and/or lateral, forces from the main frame to the sub-frame while allowing substantially free vertical motion of the sub-frame relative to the main frame. A grinding unit is mounted on the sub-frame for grinding a paved surface at a selected grinding depth. At least one grinding unit roller is mounted on the sub-frame for supporting it at a selected elevation with respect to the paved surface. The grinding unit roller operates to control the grinding depth of the grinding unit independently of the position of the main frame. A boom is fixed to the sub-frame and extends forwardly therefrom in the direction of travel of the main frame. At least one boom wheel is mounted on the forward end of the boom for rolling on the paved surface and for supporting the boom thereon. A hydraulic mounting system hydrostatically mounts the front and rear rollers on the sub-frame so that the elevation of the front and rear rollers with respect to the sub-frame may be adjusted hydraulically. The front and rear rollers are hydraulically interconnected to equalize the vertical load carried by each roller so that the vertical movement of the boom and boom wheel will cause the sub-frame to rotate or pitch about an axis proximate to the grinding head so that the grinding depth of the grinding head will remain substantially constant in the presence of vertical motion of the boom and boom wheel.
O'Konek, U.S. Pat. No. 6,499,809 discloses a pavement grinder that includes a cutting device having a separate grinding carriage with carriage drive wheels. A rotating arbor hangs from underneath the carriage. A support device supports the grinding carriage from above. A first motor drives the arbor in a first direction, and a second motor drives the carriage drive wheels in an opposite direction. The carriage drive wheels remain in contact with the pavement when the grinding carriage is in a raised position. A depth controller is mounted on the carriage for raising and lowering the carriage relative to the carriage drive wheels. Additional road cutting machines are disclosed in Pentith, U.S. Pat. No. 3,767,262; Gowler, U.S. Pat. No. 3,888,542; and Heckenhauer et al. U.S. Pat. No. 4,154,481.
Despite the various features and benefits of the structures in the forgoing disclosures, there remains a need for a pavement grinding apparatus designed to remove bumps and other irregularities from the surface of a road, runway, taxiway, or other pavement that provides for a plurality of modes of operation and control of the grinding element in relation to the pavement surface to achieve the desired pavement profile.